Hidden Assumptions that make Equilibrium Calculations Easier What Do We Do When the Approximation Fails?
based on the following reaction:

2H₂O(g) 2H₂(g) + O₂(g)
K_c = 2 x 10^-42 (at 25^oC)
-Starting with 0.10 M H₂O(g) , what would be the best strategy for solving for the equilibrium concentrations of H₂O, H₂ and O₂?

Question

Hidden Assumptions that make Equilibrium Calculations Easier What Do We Do When the Approximation Fails?
based on the following reaction:

2H₂O(g)

Hidden Assumptions that make Equilibrium Calculations Easier What Do We Do When the Approximation Fails? based on the following reaction: 2H<sub>2</sub>O(g) 2H<sub>2</sub>(g) + O<sub>2</sub>(g) K<sub>c</sub> = 2 x 10<sup>-42</sup> (at 25<sup>o</sup>C) -Starting with 0.10 M H<sub>2</sub>O(g) , what would be the best strategy for solving for the equilibrium concentrations of H<sub>2</sub>O, H<sub>2</sub> and O<sub>2</sub>? A) Since the change in the concentrations are expected to be large going to equilibrium, the equation will have to be solved exactly. B) Since the changes in the concentrations are expected to be large going to equilibrium, it is best to assume that all of the H<sub>2</sub>O(g) is converted to products and then calculate the equilibrium concentration. C) Since the changes in concentrations are expected to be small going to equilibrium, it is best to assume that the changes will be small relative to the initial concentration of H<sub>2</sub>O(g) . D) Since the changes in concentrations are expected to be small going to equilibrium, it is best to assume that the changes will be large relative to the initial concentration of H<sub>2</sub>O(g) . E) There is no reasonable way to even approximate the answer to this problem.

2H₂(g) + O₂(g)
K_c = 2 x 10^-42 (at 25^oC)
-Starting with 0.10 M H₂O(g) , what would be the best strategy for solving for the equilibrium concentrations of H₂O, H₂ and O₂?

Quizplus · Accepted Answer

The best strategy for solving for equilibrium concentrations in this scenario involves assuming that the changes in concentrations will be small relative to the initial concentration of H₂O(g). This approach simplifies the calculations by allowing the use of an approximation method, typically the ICE (Initial, Change, Equilibrium) table, where the change is considered negligible compared to the initial concentration. This is a common assumption for reactions where the dissociation is not complete or when dealing with weak acids, bases, or slightly soluble salts.

Hidden Assumptions That Make Equilibrium Calculations Easier What Do We